Commitments and Contingencies - Future Minimum Lease Payments (Details)
$ in Thousands
Mar. 31, 2018
USD ($)
Future minimum lease payments due under operating leases  
2018 (remaining nine months) $ 3,821
2019 5,093
2020 5,135
2021 4,973
2022 2,191
Thereafter 1,704
Total $ 22,917